The present invention is generally directed to toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner compositions. In embodiments, the present invention is directed to the economical in situ chemical preparation of toners without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with a volume average diameter of from about 1 to about 25, and preferably from 1 to about 10 microns and narrow GSD of, for example, from about 1.16 to about 1.31 as measured on the Coulter Counter can be obtained, and wherein subsequent to preparation there is grafted onto the toner surface polymer primarily to improve the toner triboelectric characteristics and improve the toner admix properties. In embodiments, thus after the toner is prepared by emulsion/aggregation/coalescence methods as illustrated herein, the toner is washed, surfactant, initiator, and additional monomer are added, thereafter polymerization is accomplished and there is formed on the toner surface a layer of polymer obtained from additional monomer. The resulting toners can be selected for known electrophotographic imaging, printing processes, including color processes, and lithography. In embodiments, the present invention is directed to a process comprised of preparing, or providing a latex or emulsion mixture comprised of suspended sub micron resin particles of, for example about 0.01 microns to 0.5 microns in volume average diameter, in an aqueous solution containing an ionic surfactant such as an anionic surfactant in the amounts of 0.5 to 10% and a non ionic surfactant in an amount of 0.1 to 5% (weight percent throughout unless otherwise stated) and shearing this mixture with a pigment dispersion comprised of finely grounded pigments which are in the range of 50 to 250 nanometers dispersed in non ionic surfactant, optional toner additives such as release agents, in an aqueous mixture containing a counterionic surfactant such as a cationic surfactant, which is in the range of 0.1% to 5% by weight, thereby causing a flocculation of resin particles, pigment particles and optional charge control agent, followed by heating at about 5.degree. to about 40.degree. C. below the resin Tg and preferably about 5.degree. to about 25.degree. C. below the resin Tg while stirring of the flocculent mixture, which is believed to form statically bound aggregates of from about 1 micron to about 10 microns in volume average diameter, comprised of resin, pigment and optionally charge control particles, and thereafter heating to coalesce the formed bound aggregates about above the Tg (glass transition temperature) of the resin. The size of the aforementioned statistically bonded aggregated particles can be controlled by adjusting the temperature in the below the resin Tg heating stage. An increase in the temperature can cause an increase in the size of the aggregated particle. Heating the mixture about above, or in embodiments equal to the resin Tg generates toner particles with, for example, an average particle volume diameter of from about 1 to about 25 and preferably from about 1 to about 10 microns. It is believed that during the heating stage, the components of aggregated particles fuse together to form composite toner particles, followed by the toner particles being washed several times, such as about 10 times in embodiments with water to remove the surfactants. Subsequently there is formed on the toner surface a polymer layer by adding monomer, initiator and optional surfactant to the toner obtained, polymerizing the monomer by heating, cooling, and washing.
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic or basic polar groups and a coloring agent. The polymers selected for the toners of the '127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this '127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. Also, see column 9, lines 50 to 55, wherein a polar monomer, such as acrylic acid, in the emulsion resin is necessary, and toner preparation is not obtained without the use, for example, of acrylic acid polar group, see Comparative Example I. In U.S. Pat. No. 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner.
Emulsion/aggregation/coalescence processes for the preparation of toners are illustrated in a number of patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. No. 5,290,654, U.S. Pat. No. 5,278,020, U.S. Pat. No. 5,308,734, U.S. Pat. No. 5,346,797, U.S. Pat. No. 5,370,963, U.S. Pat. No. 5,344,738, U.S. Pat. No. 5,403,693, U.S. Pat. No. 5,418,108, U.S. Pat. No. 5,364,729, and U.S. Pat. No. 5,346,797. These toners can then be surface treated, and more specifically, have a polymer grafted to the surface thereof by the adding thereto of monomer and polymerizing.